Method of forming brake drums or like structures



June 14, 1938. c, s. ASH 2,120,595

METHOD OF vFORMING BRAKE DRUMS OR LIKE STRUCTURES Filed Dec. 17. 1934 3 Sheets-Sheet 1 INVENTOH ATTORNEY 8 itr June 14, 1938.

Filed Dec. 1?. 1954 c. s. ASH 2,120,595

METHOD OF FORMING BRAKE DRUMS OR LIKE S TRUCTURES 5 Sheets-Sheet 2 FIG.5.

BY /W ATTORNEYS June 14,1938 c, s, A H 120,595

METHOD OF FORMING BRAKE DRUMS OR LIKE STRUCTURES Filed Dec. 1'7, 1934 5 Sheets-Sheet 3 FIG].

i CHARLES SLAsu TTTTTT EYS Patented June 14, 1938 UNITED STATES PATENT orricr.

METHOD OF FORIVHNG BRAKE DRUMS OR LIKE STRUCTURES Application December 17, 1934, Serial No. 757,959

6 Claims.

The invention relates to the manufacture of brake drums and similar structures from sheet metal blanks of uniform gauge. It is the object of the invention to form from such a blank a structure having different portions thereof of varying thicknesses and more particularly to form the cylindrical flange for the braking surface of greater thickness than the web portion of the drum. To this end the invention consists in the method and apparatus as hereinafter set forth.

In the drawings: 7

Fig. 1 is a cross section through an apparatus for bowling a blank of uniform gauge to form a'web and substantially cylindrical flange;

Fig. 2 illustrates the manner of upsetting the flange portion of the blank to increase the thickness thereof;

Figs. 3 and 4 illustrate successive steps of forming a peripheral flange at the end of the cylindrical portion of increased thickness;

Figs. 5, 6, 7, 8 and 9 are views similar to Figs. 1 to 4 illustrating a modified method;

Figs. 10, 11, 12 and 13 are enlarged views illustrating the upsetting operation;

Fig. 14 is a diagrammatic view illustrating the geometrical principle involved inthe modified construction illustrated in Figs. 5 to 10.

In the manufacture of drums from sheet metal blanks of uniform gauge, the usual method is to first cut a circular blank from the sheet metal, then to bowl this blank by the operation of dies or other means to form a web portion and a cylindrical flange. During this bowling operation the diameter of the peripheral portion of the blank is contracted, which may result in a slight upsetting or thickening of the gauge. However, as generally performed, the metal flows to in crease the length of the cylindrical flange instead of increasing the thickness. In other words, the measurement of the cross sectional contour from the center of the bowled blank to the outer edge of the cylindrical flange would show an increase in length over the radius of the original flat blank. For use in brake drums it is desirable to have a greater thickness in the cylindrical flange than is required for proper strength in the web portion of the drum. However, as above described, this increase in thickness is not obtained by the usual method of bowling the blank. Consequently the amount of metal used and the weight of the drum are greater than required for proper strength, inasmuch as it is essential that the brake flange should be of the proper thickness.

To overcome this defect I have devised a method and apparatus through which the thickness of the flange portion of the bowled blank may be increased over the thickness of the web portion clamped by a male die G, leaving sufficient space.

between the concentric cylindrical surfaces F and G for the increased thickness of flange which is desired. An annular die H is then forced into the space between surfaces G and F engaging the end of the flange of the bowled blank E and compressing and upsetting the same until it is enlarged in thickness to correspond to the space between said surfaces F and G. It will be understood that the diameter of the original flat blank is so selected as to obtain the desired length of the thickened cylindrical flange E after the upsetting operation.

The blank with the thickened flange E is then subjected to die operations illustrated in Figs; 3 and 4 which form thereon an outwardly extending peripheral flange E With the construction as, above described, the upsetting of the blank is effected in a chamber or space between the dies which is equal in radial dimension to the thickness of the finished flange.

However, during the upsetting operation thisv space is greater than the thickness of the flange so that there is nothing to restrain the latter from wrinkling. To overcome this objection I have devised a construction and a modified method in which the chamber for receiving the thickened flange is increased in radial depth just in proportion to its diminution inlength so that during the entire upsetting process theinner' and outer surfaces of the blank are in. contact with the corresponding surfaces of the die. The apparatus shown in Figs. 5 to 9 is similar in general construction to that illustrated in Figs. 1 to 4, but in place of spaced dies which are exactly cylindrical between which the flange of the blank is upset, I employ dies which are slightly conical. The amount of taper of these conical dies is so selected that by moving the outer die downward with the upsetting member, the space between this die and the inner conical member will be radially enlarged just in proportion to the increase in thickness of the metal due to upsetting. In other words, the volume of the space between the conical dies which is occupied by the blank remains constant during the upsetting operation although it is diminished in length as it is increased in radial depth. This is illustrated diagrammatically in Fig. 14 in which the rectangle a, b, c, d represents the cross section of a blank before upsetting and e, f, c, g is a rectangle of equal area but of diminished length and increased thickness. 71. is the point of intersection of the lines (1-4) and eg, and it will be understood that the line a.h is equal to the amount of contraction in length and the line eh, is equal to the amount of increase in width during change from the rectangle a, b, c, d to the rectangle e, f, c, g. By connecting the points ae by a .straight line and then moving the right angle d.a b with its apex a in the line ae and its sides a--cZ-ab maintained parallel respectively to their original position, there will be no change in area of the rectangle but it will be progressively decreased in length and increased in width.

This principle is further illustrated in Figs. 12 and 13 in which I is an inner conical die member and J is an outer conical die member which are movable in relation to each other along a common axis parallel to the line K-K. In Fig. 12 the space between these die members is of a length and width equal to the length and thickness of the blank before upsetting and in Fig. 13 the length has been shortened and the width increased to correspond to the upset blank. At each point during the movement, the cross section of the blank will remain constant and its sides will be in contact with the sides of the dies I and J.

With the apparatus shown in Figs. 5 to 11, the principle is the same as that shown in Figs. 12 to 14, but to facilitate the operation, the periphery of the bowled blank has first formed thereon a radial flange which is clamped between die members. Fig. 5 illustrates the first operation of bowling the blank to form a substantially cylindrical flange L terminating in an outwardly flaring flange L. In Fig. 6 this bowled blank is further pressed in dies to flatten the flaring flange L into a radially extending flange L to also refashion the web portion of the blank as indicated at M and to change the cylindrical portion L into a slightly coned portion as indicated at N. The blank is then upset as shown in Figs. 7 and 8, and enlarged views 10 and 11 the flange L being clamped between die members 0 and O which together move downward in relation to the central die members P and Q between which the web of the blank is clamped. The operation will be the same as shown in Figs. 13 and 14.- resulting in an upset, thickened and slightly tapered flange R. The blank is then refashioned as shown in Fig. 9 to change the tapered flange R into a cylindrical flange R.

What I claim as my invention is:

1. A method of forming brake drums or like structures comprising the cutting of a blank from sheet metal of uniform gauge, bowling said blank to form the web portion and flange portion of the drum and applying endwise upsetting pressure to the flange portion to reduce the length and uniformly increase the thickness throughout its length.

2. The method of forming brake drums or like structures comprising cutting a blank from sheet metal of uniform gauge, said blank being of a mass equal to that of the fashioned drum, and of a diameter greater in measurement than the cross sectional contour of the fashioned drum,

bowling said blank to form a substantially cylin- V ,drical flange of greater length than in the fashioned drum, and endwise compressing said flange to upset the same, reducing its length and uniformly increasing its thickness throughout its length.

3. The method of forming brake drums or like structures comprising cutting a blank from sheet metal of uniform gauge, said blank being of a mass equal to that of the fashioned drum and of a diameter greater in measurement than the cross sectional contour of said fashioned drum, bowling said blank to form a substantially cylindrical flange of greater length than in the fashioned drum, placing the bowled blank with its flange between concentric dies and endwise compressing said flange while between said dies to reduce its length and uniformly increase its thickness throughout itslength.

4. The method of forming brake drums or like structures comprising cutting a blank from sheet metal of uniform gauge, said blank being of a mass equal to that of the fashioned drum and of a diameter greater in measurement than the cross sectional contour of said fashioned drum, bowling the blank to form a substantially cylindrical flange, placing the bowled blank between dies having concentric portions with a space therebetween equal in length and radial depth to the flange of the bowled blank and relatively moving said dies to simultaneously diminish the length and increase the radial depth of said space while maintaining a substantially constant cross sectional area.

5. The method of forming brake drums or like structures comprising cutting a blank from sheet metal of uniform gauge, said blank being of a mass equal to that of the fashioned drum and of a diameter greater in measurement than the cross sectional contour of said fashioned drum, bowling said blank to form a substantially cylindrical flange thereon of greater length than in the fashioned drum, endwise compressing said flange to diminish the length thereof, holding said flange during said upsetting operation between outer and inner die members and relatively moving said outer and inner die members during said upsetting operation to increase the space therebetween proportional to the diminished length of the flange to maintain at all times a substantially equal cross sectional area.

6. In a method of forming brake drums and the like from sheet metal blanks, the stepof holding the flange portion between dies having portions contacting the opposite sides and opposite ends thereof and moving said dies to increase the distance between the sides and diminish the distance between the ends thereof maintaining at all times a uniform cross section and thereby uniformly increasing the thickness and diminishing the length of said flange. V v

CHARLES S. ASH. 

